The prior art discloses an apparatus for manufacturing thin-walled bodies of revolution comprising an expander which is mounted rotatably about a longitudinal axis and a feeder for supplying liquid high-temperature resin, said feeder being mounted above the expander so as to be movable therealong (U.S. Pat. No. 6,090,326 A, published on Jul. 18, 2000). A disadvantage of the known apparatus is the impossibility of using it for manufacturing semi-finished biodegradable polymeric stents. Namely, it lacks the ability to heat the feeder to prepare a polymer melt.
The prior art discloses an apparatus for coating hollow cylindrical articles comprising a tube rotation unit, an outer coating unit comprising a spray head with its movement mechanism (SU1206547 A1 published on Jan. 23, 1986). A disadvantage of the known apparatus is the impossibility of using it for manufacturing semi-finished biodegradable polymeric stents. Namely, it is unable to heat the feeder to prepare the polymer melt, and the lack of the means for expander heating deteriorates the quality of the article.
The closest prior art to the claimed solution in its technical essence is an apparatus for molding thin-walled bodies of revolution from polymer materials known from RU2010712 C1 published on Apr. 15, 1994. The apparatus comprises a heatable expander which is mounted rotatably about a longitudinal axis and a feeder for supplying moldable material, said feeder being mounted above the expander so as to be movable therealong.
A disadvantage of the known apparatus is the impossibility of using it for manufacturing semi-finished biodegradable polymeric stents. At elevated temperatures biodegradable polymers lose their properties; therefore, their feeders are made in the form of an extruder, where the polymer is heated not to a liquid but to a viscoelastic state. Wherein, the polymer exiting the extruder may exert considerable pressure on the expander, which will push the extruder away from the surface and in turn distort the defined geometrical dimensions of the semi-finished article. Therefore, a carriage with the feeder should be secured very rigidly with respect to the axis of the tube. In addition, when performing multilayered semi-finished article molding, which may be necessary to obtain the specified mechanical and biological characteristics, a tip of the expander will plough into in a polymer softened at an elevated temperature, which will also distort the geometrical shape of the semi-finished article.